6 Replies

The easiest way to do this is to build a new server with 2008 R2 on the server, promote it, raise function level to 2K8 them once all roles are transferred over and the domain replication is working properly, dcpromo the old 2K3 servers and remove them from the domain. Then, your other server can be built as a 2K12 server and the same process to get them domain up to a 2K12 level can be followed. This should preserve your GPO as well.

I would install the new 2012 DC upgrade all the schema, wait a day or 2 then demote the 2k3 DCs. Only after everything is running well would I upgrade the functional level (This is an unreversable process) and honestly usually doesn't do a whole lot. You actually can't upgrade the domain/forest functional level until the old DCs are demoted.

It should work fine. With server 2012 the DC process is even easier than in the past. It will update the schema for you automatically just by following the prompts. I think you might be confusing domain/forest fuctional levels with having a domain controller of that type. Just because you have a 2012 DC does not mean you need to run at a 2012 domain functional level.